This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The investigators will test the hypothesis that resting and central hypovolemia-induced increases in MSNA are similar in the arm and leg of older adults. The investigators also hypothesize that increases in MSNA during graded central hypovolemic stress are associated with blunted vasoconstrictor responses in both the arm and leg of older compared to younger adults.